Device for thawing an ice separator used in a system comprising a cold gas refrigerator



April 14, 1959 BLOEM v DEVICE FOR THAWING AN ICE SEPARATOR USED IN A SYSTEM COMPRISING A COLD-GAS REFRIGERATOR Filed Jan. 12, 1955 INVENTOR ALDERT TEUNIS BLOEM AGENT United States Patent DEVICE FOR THAWING AN ICE SEPARATOR USED lN'A SYSTEM COMPRISING A COLD-' GAS REFRIGERATOR Application January 12, 1955, Serial No. 481,433

Claims priority, application Netherlands January 15, 1954 2 Claims. (Cl. 62-154) The invention relates to a device for thawing an ice separator used in a system comprising a cold-gas refrigerator. The term coldgas refrigerator is to be understood to mean herein a so-called refrigerator operating on the reversed hot-gas engine principle. It is known that these refrigerators may be constructed in various ways, for example in the form of a displacer-piston machine, of a double-acting machine, of a machine, the cylinders of which are at an angle to one another or of a machine of which the working space is combined with that of a hot-gas engine. By means of these machines a large temperature difference, for example of -.,-100 C. and even of --200 C. may be bridged in one step. Owing to this property these machines may be used successfully in systems for cooling and condensing gases or gaseous mixtures or in systems in which gaseous mixtures are separated into fractions.

These gaseous mixtures to be cooled, condensed or separated often contain impurities, which must not be contained in the final product. These impurities may be extracted from the gases, when they are still in the gaseous state. This may be carried out by means of chemical substances, but it is, as a rule, to be preferred to separate by freezing out those impurities which have a higher thaw point than the products to be obtained.

The constituents frozen out will accumulate, as a rule, in the ice separator, so that from time to time this ice separator must be cleaned.

The ice separators may for example be cleaned by heating them, so that the ice thaws or evaporates.

The device according to the invention may be employed successfully to this end. This device has the feature that it comprises a fan, by which air is conveyed to a heating device after which the air thus heated can be supplied to the ice separator while the duct system of the device comprises a safety valve.

According to the invention it has been found that sometimes the ice separator may be filled locally with ice to such an extent that the resistance to the air to be blown through the ice separator may be too high. This may result in that the electric motor driving the fan is overloaded, while the heating device can draw only an insuflicient quantity of air, so that it may be overloaded. By means of the safety valve the air or part thereof may, in such a case be blown away. The return valve is preferably arranged between the heating device and the ice separator so that the heating device is loaded invariably to the same extent.

The heating device may, of course, be constructed in various ways, but an electric heating helix will, as a rule, be preferred. The fan may be driven by the motor driving the cold-gas refrigerator; however, since the thawing device need be used only periodically, it will, in general, be desirable to provide the fan with its own motor.

According to one aspect of the invention, the heating air is pushed against the direction of flow of the gaseous mixture to be cooled through the ice separator.

The invention will be described with reference to one embodiment.

Fig. 1 shows a cold-gas refrigerator, comprising a device according to the invention,

Figure 2 shows a device for thawing the ice separator.

The cold-gas refrigerator shown is a displacer piston machine and comprises a displacer-piston 1 and a piston 2, which move up and down in a cylinder 3 with a substantially constant phase difference. To this end the displacer piston 1 is coupled by means of a connectingrod system 4 with ,a crank of a crankshaft 5, whereas the piston 2 is coupled by means of a connecting-rod system 6 with a crank of the same crankshaft 5. The space 7 above the displacer piston is the so-called freezing space, which communicates through ducts 8' in a freezing section 9, a regenerator 10 and ducts 11 in a cooler 12 with a space 13, which is termed the cooled space. The refrigerator is driven by a motor, for example an electric motor 14. The refrigerator contains a suitable gas, for example hydrogen or helium and since the piston and the displacer piston move with a phase difference, expansion takes place mainly in the freezing space 7 and compression mainly in the cooled space 13, so that heat can be supplied to the freezer at a low temperature, for example at -200 C. and the machine operates as a refrigerator. The freezer comprises two sections, i.e. a section 9 associatedwiththe ducts 8 and a section located outside the machine proper and constituted by a support, which has three parts in this embodiment, i.e. a part 15, a part 16 and a part 17. The heat resistance of these parts is different. The wall thickness of the part 15 for example is materially larger than that of the part 16 and the wall thickness of the latter exceeds that of the part 17. The parts 16 and 17 are interconnected by means of a connecting piece 18, having satisfactory heat conductivity. The parts of the support are provided with extensions, constructed in the form of transverse partitions, i.e. the transverse partitions 19, 20 and 21, in which apertures are provided.

It is evident from Fig. 2 that these apertures are in staggered positions in two successive extensions. The transverse partitions with the aperture 22 of the part 15 and the transverse partitions 20 with the apertures 23 of the part 16 extend to a wall 24 surrounding these parts whereas the transverse partitions 21 with the apertures 25 associated with the part 17 extend to a Wall 26. The part 17 is insulated from the wall 24. The heat exchanger is surrounded by a wall 27, having heat insulation properties.

The gas to be cooled is supplied through apertures 28 and flows through the apertures 25 of the transverse partitions 21 in upward direction, then through an aperture 29 in the connecting piece 18 and through the aperture 22 and 23 in the transverse partitions 19 and 20 respectively and along vanes 30 of the freezer section 9. The cooled medium leaves the heat exchanger in the liquid state and is conducted away through the duct 31. On the transverse partitions 21 associated with the support 17 the watervapour is deposited, if air is cooled and the spaces 32 between these plates are so large that it takes comparatively long time before these spaces are completely filled with ice. In the spaces 33 between the transverse partitions 20 carbonic acid may be separated out; the transverse partitions 19 serve mainly for further cooling of the medium. The relative temperature division among the transverse partitions 19, 20 and 21 is such that the mean temperature difference between the successive transverse partitions associated with one of these groups is not more than for example 10 C. The

Patented Apr. 14, 1959- meantemperature-of that transverse partition at which the separation starts is not more than 20 preferably not more than C. lower than the separation point of that component of the medium as it is supplied to the extensions. The separation will start, in accordance with the quantity of medium flowing through the heat exchanger, atom of the transverse partitions, located for example on the bottom side of the heat exchanger, where the medium enters. If, after some time, such a quantity of ice has been separated out in the heat exchanger, that one or more of the spaces 32 or 33 is substantially filled out, it will be desirable to stop the supply of medium to be cooled to the heat exchanger, while at the same time no cold must be any longer withdrawn from the heat exchanger. By blowing in hot air, the solid carbonic acid will volatilize in the space 33, while the icein the spaces 32 is changed into water, which flows down through apertures. in the, edges of the transverse partitions and can be conducted away from the ice separator through a duct 35.

The device for thawing the ice separator comprises a fan.36, which may be driven by an electric motor 37. The fan comprises an outlet duct'38, having a heating element 39 and a duct 40 which can be connected to the ice separator. The duct 40 has a safety valve 41, which is urged by a spring 42.

If the ice is to be removedfrom the ice separator, the duct 40 is connected to the outlet duct 31. The fan 36thus pushes the air sucked in against the direction of flow of the gaseous mixture to be cooled through the, ice separator, so that the ice thaws and the carbonic acid evaporates. The condensate produced is conducted away through the duct 35.

C.- lower,

It will be obvious that the device according to the invention may, as an alternative, be used with an ice separator, from the support "'of which heat is withdrawn in a different manner, for example by means of evaporating oxygen. As an alternative, instead of using hot air, use may be made of other gases.

What is claimed is: o 1

l. A heating device for thawing an ice separator associated with apparatus including a cold-gas refrigerator comprising; a fan, means for driving said fan, means for supplying the air produced by said fan tosaid ice separator, a heating device located in the last-mentioned means between said fan and said ice separator, and a normally closed, valve arranged in said last-mentioned means between said heating device and said ice separator and responsive to pressure to maintain the fan flow through said supply means and heater thereby preventing the overheating of said heating device.

2. A heating device as claimed in claim 1 further comprising a discharge pipe wherein hot air is expelled from said supply means through said discharge pipe and into one end of said ice separator and against the direction of flow of the gaseous mixture to be cooled through said ice separator.

References Cited in the file of this patent UNITED STATES PATENTS 1,594,906 Gross Aug. 3, 1926 2,113,680 De Baufre Apr. 12, 1938 2,337,474 Kornemann Dec. 21, 1943 2,563,042 Iaubert Au 7. 

